Method for developing an anatomic space

ABSTRACT

A fluid operated retractor for use in surgery. The retractor has a portion which is expandable upon the introduction of fluid under pressure. The expandable portion is made of a material strong enough, and is inflated to enough pressure, to spread adjoining tissues within the body. The retractor is especially useful in fiber optic surgery because it can be inserted percutaneously through a small opening then expanded to a much larger dimension when in the desired location, to retract tissue from within. The retractor may be used to spread a joint such as a knee joint or a shoulder joint, or may be used to separate tissue planes generally, to improve visualization and create a working space for the surgeon.

RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 08/727,968 filedOct. 9, 1996, which is a divisional of U.S. application Ser. No.08/462,420, filed on Jun. 5, 1995, now U.S. Pat. No. 6,171,299, which isa divisional of U.S. application Ser. No. 08/195,337, filed on Feb. 14,1994, now U.S. Pat. No. 5,514,153, which is a continuation-in-part ofU.S. application Ser. No. 07/792,730, filed on Nov. 15, 1991, now U.S.Pat. No. 5,295,994, and a continuation-in-part of U.S. application Ser.No. 08/054,416, filed on Apr. 28, 1993, now abandoned, which is adivisional of U.S. Ser. No. 07/487,645 filed on Mar. 2, 1990, now U.S.Pat. No. 5,331,975. The benefit of the earlier filing date ofaforementioned applications is hereby claimed.

BACKGROUND OF THE INVENTION

The present invention relates to medical devices, and particularly toexpandable medical devices such as cannulas, catheters, retractors, andsimilar devices.

Existing cannulas and/or retractors as used in endoscopic surgery todayare passive devices which are fixed in length and width. They cannot bevaried intraoperatively in length and width to accommodate largerdevices or varying size devices through the skin.

Skin and subcutaneous (subsurface) tissues are viscoelastic: they willgradually stretch without tearing. Once the tissue is slowly stretchedit maintains its expanded condition for a period of time. Alternatively,the tissue can be stretched further, for example to progressivelystretch out an incision. Then, after relaxation, the tissue will regainits original unstretched condition without having been damaged.

Current methods used for retracting tissue and improving visualizationare mechanical separation using metal refractors during open surgery, orthe direct pressure of an unconfined flow of fluid such as water or CO₂during fiberoptic surgery. A typical mechanical external fixator haspins driven through the bones and mechanically distracts the elements ofthe joint. Problems with the water method include fluid extravasationincluding into and through the tissue itself. Increased pressure andswelling result in the area, resulting in edematous or swollen tissue.Excess pressure from mechanical refractors may cause necrosis or tissuedeath. With these methods, it is impossible to monitor the pressurebeing applied to the body tissues, and tissue damage or necrosis canresult.

While operating from within the body, i.e., fiber optic assisted surgeryas opposed to open surgery, there is no known way to selectively move orretract tissue, either hard tissue such as bone or soft tissue, out ofthe way to improve visualization. No device in use adequately allows asurgeon to create an actual space or expand a potential space in thebody, by separating adjacent layers of tissue. The prior art does notdisclose a retractor which is powerful enough and made of a materialwhich is strong and resilient enough to, for example, separate tissueplanes from within. Such a device, especially in the field of fiberoptic surgery, would allow a surgeon to visualize and operate withoutusing the conventional bulky and awkward mechanical Detractors whichrequire large open incisions. Such a device would also permit workingwithin the body without damaging a great deal of tissue in the pathbetween the skin opening and the working area, by minimizing theexternal orifice or skin incision.

SUMMARY OF THE INVENTION

The present invention is a system of refractors and/or cannulas withwhich a surgeon can use to take potential spaces within the body andturn them into existing spaces safely and easily and controllably inorder to safely visualize appropriate tissue and operate. The cannulaand/or retractor selectively moves appropriate tissue out of the way toenable a surgeon to see and work better within the body, and selectivelymoves body parts such as joint parts or soft tissue planes in order tocreate a space between the tissues for visualization and for working.

A cannula and/or retractor of the present invention may have afluid-operated portion such as a balloon or bladder to retract tissue,not merely to work in or dilate an existing opening as for example anangioscope does. The fluid-filled portion is flexible, and thus thereare no sharp edges which might injure tissue being moved by theretractor. The soft material of the fluid-filled portion, to an extentdesired, conforms to the tissue confines, and the exact pressure can bemonitored so as not to damage tissue. The expanding portion is lessbulky and more compact, and the pressure it applies at the tissue edgescan stop bleeding of cut tissue. These are all features not possessed bya conventional mechanical retractor.

With a typical mechanical retractor, the opening in the skin and thenceinwardly must be larger than the surgical area being worked upon, inorder to be able to get the mechanical retractor into position. Thesurgeon must damage a large amount of tissue which may be healthy, inorder to expose the tissue to be worked on. The cannula and/or retractorof the present invention minimizes damage to tissue in the way of thetissue the surgeon needs to expose, which was previously cut in a largeopen exposure. With the cannula and/or retractor of the presentinvention, the opening at the skin is smaller at the skin where thedevice is inserted, and wider at the location inside the body where thecannula and/or retractor is expanded. The cannula and/or retractor isfirst placed into the body in an unexpanded condition, and then, as itis expanded, pushes tissue out of the way in deeper layers of the bodyone can see and safely operate on affected tissue. Thus, less undesiredtissue damage occurs.

The bladder is pressurized with air or with water or another fluid. Thefluid used in the bladder must be safe if it accidentally escapes intothe body. Thus, besides air, such other fluids as dextrose water, normalsaline, CO₂ and N₂ are safe. The pressure in the bladder is monitoredand regulated to keep the force exerted by the retractor at a safe levelfor tissue to prevent tissue necrosis. The retractor can exert apressure on the tissues of as high as the mean diastolic pressure of 100mm of mercury, or higher for shorter periods of time, while still beingsafely controlled. Typical inflatable devices such as angioscopes do nothave anywhere near the strength, or the ability to hold enough fluidpressure, or shapes to retract tissue as described herein. As comparedto prior art devices, the retractor of the present invention operateswith greater pressure within the bladder, since it is made of strongermaterials such as Kevlar or Mylar which may be reinforced with stainlesssteel, nylon, or other fiber to prevent puncturing and to providestructural shape and support as desired. Such materials are strongenough to hold the necessary fluid pressure of about several pounds orup to about 500 mg Hg or more and exert the needed force on the tissueto be moved. The choice of material is well within the ability of onefamiliar with such materials and accordingly will not be gone into infurther detail herein. The present retractor is thus able to exertsubstantially more force on adjoining tissues than a prior art device.The shapes of the refractors are specific for each application, and mayinclude separate variable chambers which are sequentially controllable,to control the direction of tissue retraction.

Surgeons operate along tissue planes. Once a surgeon finds a tissueplane, he dissects along it, starting the separation process with theknife. The cannula and/or retractor holds the tissue layers apart andhelps and eases in defining and further separating the tissue layers asthe surgeon operates along the tissue planes, helping to spread anddefine the planes. The cannula and/or retractor helps to separate thetissue layers, increasing the space for operating, and improving thesurgeon's ability to separate and visualize, leading to better and safersurgical technique.

A preferred use for the present retractor is in the field of fiber opticsurgery, including endoscopy, arthroscopy, laparoscopy, etc. whichrequire looking into and operating within a limited space with a fiberoptic light and camera. The bladder expands into an area of softtissue—for example the bursa—and pushes it out of the way. The bladdercan be left in place during the operation, or it can be deflated andremoved, and the arthroscope and other instruments can be put into thespace created. to The bladder may be a bellows type device in which thematerial does not stretch but which expands when pressurized from withinand which is collapsed by the use of suction. In this case, it wouldpreferably be made of a polymer of the class including Kevlar or Mylarfabric for strength and structural integrity. The bladder may generallyalso be made from any very thin walled polymer.

The bladder may also be made from a biocompatible and/or biodegradablematerial, so that if it can not be removed from the body for somereason, or if the surgeon desires to keep the bladder in place in thebody for a period of time, it will not damage the tissue and mayeventually be reabsorbed into the body. Such a biodegradable bladder maybe left under the skin postoperatively to stop postoperative bleeding orto keep tissue expanded. Alternatively, the bladder may be made of astretchable material which stretches when pressurized from within, andthen collapses partially of its own accord when depressurized or alsowith the help of suction. The retractor may be transparent for bettervisibility, but it need not be for some applications. Also, theretractor can be disposable. The material choice is within the skill ofthe art. One surface of the bladder may be made of or have thereon areflective surface to reflect light to see around a corner.

A most typical construction for the cannula and/or retractor of thepresent invention is an inflatable bladder situated on the end of ashaft, which may be flexible or rigid,-which is pushed through an extraopening in a scope or cannula or through a separate portal, and whichexpands at the end of the shaft.

The retractor can be located on a scope, either on the end thereof ormovable axially through a channel along the length of the scope. Theretractor can alternatively be mounted on a cannula. The retractor canbe mounted on a separate shaft passing through an existing channel in acannula; it can be inserted through a separate hole in the cannula orthe scope; or it can be inserted through a separate opening in the body.The shaft with a retractor on the end can be pushed or slid through thecannula, side by side with a scope. Alternatively, the bladder canexpand out of, then recess back into, a groove on a cannula or scope.The retractor can be used to create a space right by the scope, orpossibly at a location spaced from the end of the scope.

The bladder itself can be round, eccentric, oval, conical, wedge-shaped,U-shaped, curved, angled, or it may be in any shape desirable tooptimize the particular application. The bladder may be irregularlyshaped when inflated, that is, it may expand to a greater radius in thearea where it is desired to look (where greater exposure space isneeded).

Vacuum can be used to deflate the bladder. The bladder may then beremoved by sliding it out the portal directly.

The present invention is described herein as relating to cannulas and/orrefractors. A cannula is a device for insertion into or through bodytissue to provide a working passage for surgical instruments, scopes,etc., as in endoscopic or arthroscopic surgery. A catheter, on the otherhand, is an artificial fluid passage primarily used for insertionthrough an existing body opening. The two types of devices have verydifferent structures and structural requirements. For example, acatheter is usually flexible, very small in diameter, and not suitablefor maintaining a working passage through normally closed body tissues,while a cannula is more rigid, larger in size, and designed specificallyto provide a working passage for surgical instruments and scopes throughnormally closed body tissues. It should be understood, however, thatmany of the features of the present invention can with suitablemodifications be applied to the catheter art. Accordingly, the presentinvention is not limited to cannulas per se, but may be applicable tocatheters or other devices also.

The present invention defines an active cannula or sleeve which doesmore than merely maintain a channel or passage. It is an active deviceusable to enlarge a channel or passage, to position a scope orinstrument, to move or locate tissue, etc. The cannula can vary in sizeor shape as needed, intraoperatively. Typically, with a passive(non-expandable) cannula, a surgeon must make an incision in the skinand muscle large enough to receive the largest instrument to be passedthrough the incision to the surgical area. Because a cannula of thepresent invention is expandable, the surgeon can make a small relativelysmall incision, stretch the tissue with the expandable cannula, contractthe cannula and remove it, allowing the skin to come back to itsunstretched condition. Thus, a smaller incision can be made to fit thesame size instrument. This results in less trauma and scarring and aneasier operation.

Further, known cannulas are generally round, while skin expands (from anincision) in an elliptical fashion, between tissue planes. Thus, thepresent invention provides cannulas which are or can assume such anoncircular shape, to fit into the natural opening and cause lesstrauma.

The devices of the present invention are usable in endoscopic proceduresgenerally. The devices can be used to seal off a space; to expand anexisting space or a potential space for working or visualization; tomove tissue (for example, to stretch an incision) or to protect it.Other uses within the skill of the art but not enumerated herein arewithin the scope of the invention.

The cannulas of the present invention allow for the progressivestretching of an incision in skin or subsurface tissue in order to allowimproved exposure, while minimizing damage to the tissue by making theactual incision as small as possible.

In the arthroscopic model, a fixed cannula is placed through the skin tothe subsurface tissues into a joint. Different size working devices(shavers, burrs, scissors, punches, scope, etc.) are placed through thecannula to visualize or to work in the subsurface area at the distal endof the cannula. The cannula can be progressively expanded or stretchedradially outwardly, to stretch or expand the skin and subsurfacetissues. The cannula typically expands along its entire length, althoughit may in some cases be expandable at selected portions along itslength.

The expansion can be in a circular pattern, or it can be in an oval orelliptical or other pattern to accommodate (a) the tissue planes or (b)the instruments being inserted through the cannula.

The cannula can expand inwardly to act like a valve or a seal. Or it canexpand both inward and outward.

The cannula is preferably flexible—that is, it is bendable about an axisextending perpendicular to the longitudinal extent of the cannula. Inother words, the cannula as a long straight object is not rigid but canbend so that it is not straight. This allows the cannula to conform tothe body tissues to the extent desired.

All cannula bodies can be multi-lumen for passages through which extendstructure for control of bladders, tools, scope, etc.

In a first embodiment, a cannula may be of a stretchable material (suchas a polymer) which is introduced into the body with a trocar. Thetrocar is then removed. Progressively larger dilating devices are placedinside the stretchable cannula, as needed, to progressively stretch outthe skin and tissue to a larger size in order to introduce largerinstruments through the cannula. Each time the cannula is enlarged, thestretched tissue-remains in its stretched condition for a period of timebecause of its viscoelastic properties.

One way of stretching the cannula is by placing inside the stretchablecannula a bladder (round or elongated in the shape of a sausage, forexample) which can be inflated to uniformly stretch the cannula andtissue. The bladder can be deflated and removed, leaving the enlargedopening.

In a second embodiment, the cannula is itself inflatable for expansion.The cannula is basically an inflatable cylinder with expansions in boththe inner diameter and the outer diameter. As inflated, the deviceexpands to a preformed shape with the inner diameter following the outerdiameter and expanding outward to create a progressively larger opening.Filaments or cords can be-placed between the inner and outer walls tolimit their separation from each other. The inner wall can be morerigid.

In a third embodiment, the cannula includes one or more stretchable(inflatable or expandable) parts and one or more non-stretchable parts.The non-stretchable parts can be metal or plastic pieces such as curvedplates, joined by the stretchable elements which extend longitudinallybetween them. These stretchable elements can be bladders. As largerdevices are passed through the cannula, the stretchable portions expandand the plates move outwardly to stretch an-appropriate opening.

In any of these cases, one can monitor and control the amount ofpressure being applied to the tissue upon expansion of the cannula, soas to not exceed a certain critical pressure and damage tissue. This canbe done by monitoring the actual size of expansion, the amount of air orfluid introduced to inflate the device, the fluid pressure within thedevice, etc.

There are numerous possibilities of a cannula-with-bladder or(catheter-with-bladder) construct.

One specific example is an arthritis irrigation system. This is amulti-lumen tube which has one lumen/portal for inflow of irrigationfluid and a second portal for suction (return). The tube is flexible andhas its distal end placed in a joint to be irrigated. The tube is fixedin place by an expanding device as discussed below. Fluid flowingthrough the joint flushes out debris in the joint. The device caninclude third or additional lumens for a scope or tools to pass through.Since the tube is both flexible and fixed in place, it can remain in thepatient even when the patient is ambulatory. It thus provides apermanent passage for the surgeon to access the joint.

There can be multiple bladders at a location on the cannula,independently controlled, to position the cannula. At least one bladderis preferably at the tip of the device to expand or stretch tissue or tostabilize the device.

In any of the illustrated embodiments, the bladder can be made of adifferent material from the cannula, as opposed to, for example, aFogarty catheter which is made of all one material. This will allow forvariations in construction, with the bladder being made of one materialto better perform its functions and the cannula or other supportingmember being made of another material to better perform its functions.

The expanding (inflatable) bladders of the present invention areconstructed in various manners as set forth below. The bladder canstretch cannula walls. The bladder can move tissue and allow selectivemanipulation of tissue, even arthroscopically. The bladder also has atamponade effect, lessening bleeding in the surrounding tissues.

The bladder also distributes the refractive force, reducing stress ondelicate tissues such as nerve tissue.

There can be one or more bladders at any given location or on any giveninstrument. multiple bladders can be controlled as independentstructures or as one unit. Specific structure and control is based onthe particular application.

The surface of the material can be pebbled or roughened or ridged, orhave serrated edges, to better grip tissue and hold the retractor inposition. Of course, the surface must still remain smooth enough so thatthe retractor is easily removable without damage to the tissue itcontacts.

The bladders can expand by well in excess of 200%.

The bladder is preferably made of an elastomeric material which isstrong-enough to move tissue as desired. A suitable material for theexpandable bladder is Silastic® elastomer, which is available from DowComing in medical grades. Other suitable materials are silicone, orlatex, or PVC.

The bladder may be made of a non-elastomeric material which is strongenough to move tissue as desired. A suitable material is Mylar® fabric.A non-elastomeric material may have a more controllable shape because itwill not stretch. A non-elastomeric material will collapse inwardautomatically due to the pressure of the tissue around it, whenever itis not inflated. Many of the illustrated embodiments which are discussedas being made of an elastomeric material can also be made of anonelastomeric material.

The expandable bladder can be made of a biodegradable material. In sucha case, the biodegradable portion can be made detachable from theremainder of the retractor, so that it can be detached and left in thebody after surgery. This is useful, for example, to prevent adjacenttissue planes from scarring together after surgery. The biodegradablemass will in time disappear, allowing the tissues to adjoin after theyare healed.

The bladder can be made of a composite material—that is, a particle orfiber-reinforced material. Many suitable materials are in use inindustry. Composite materials can be made stronger while still retainingflexibility and fluid-sealing capabilities. Composite materials alsoprovide the capability to have a bladder assume a specific shape uponexpansion.

The bladder can be made of a composite biodegradable material.

The bladder(s) can be made of two different materials bonded together,such as a stretchable (low-modulus) and a non-stretchable (high-modulus)material. Mylar® and Silastic® are suitable materials, or metal for astiff material. As the inflation fluid (typically air) is introduced, ittakes the path of least resistance-and the non-stretchable materialfills out to its expanded shape first. Then the stretchable materialexpands, in a manner constrained by the already-expanded non-stretchablematerial.

The bladder can be made of a transparent material to provide a betterview of the operating area and improved visualization.

The bladder may have a dual durometer layered construction, with a thinlayer for fluid retention overlying a thicker layer for shaping. Otherlaminated constructions are possible, also.

The external shape of-the retractor when expanded, and the amount ofexpansion, are designed for the specific application on which thatretractor is to be used. For example, if the surgeon is working againstbone, he can select a retractor which is configured so that it staysflat against the bone, and expands away in the opposite direction, topush tissue away from the bone and create a working and visualizationspace next to the surface of the bone.

There are several ways to control shape of expansion-thick and thinareas (gaps, ridges, stiffened areas, etc.), fiber reinforcing, dualdurometer construction, different materials affixed together, tetheringcords, and pre-shaping.

Upon application of a given amount of force, a thinner material willstretch more than a thicker material. Thus, all other factors beingequal, an inflatable device will stretch more where it is thinner, andwill stretch less where it is thicker. This occurrence can be used tocontrol the shape into which a bladder expands when it is inflated byfluid under pressure.

As a simple example, it can readily be seen that if a bladder has onehalf made of a very thick material and one half made of the samematerial but much thinner, then upon the introduction of fluid underpressure, the thin material will stretch more quickly (easily), and thebladder will expand unevenly. The thin half of the bladder will deformmore under the same pressure until the force needed to stretch itfurther is equal to the force needed to stretch the thicker material.The half made of the thicker material will then begin to stretch, also.Thus, the thickest point on the wall will be at the crown area (farthestout).

The areas of variation in cross section can be of various shapes anddirections to control the expansion rates. For example, thecircumference of a bladder can be configured as an incomplete hoop.Thus, most of the circumference is of a thicker material, while selectedareas are thinner. Upon the introduction of fluid under pressure, thethinner areas will expand first, with each thicker area moving outwardlyas a whole.

There can be ribs around the circumference. Areas of thickness orthinness can extend longitudinally, circumferentially, radially, or inbroken segments.

A second way to control the shape of expansion is the use of a fiberreinforced (composite) material. The direction of the fibers, along withtheir number, spacing, layering, and length, controls the rate ofexpansion of the matrix material. Also, areas devoid of fibers willexpand faster or further than areas with more or stiffer fibers.

Specifically, the fibers resist stretching along their length. Thus, thebladder will stretch more in a direction across the fibers, or where thefibers are not present, than in a direction along the fibers. Fibers canbe placed at the edge of the bladder to maintain the shape of thebladder when inflated. Fibers can be layered, with one layer in onedirection and another layer in another direction to control expansion inthe other direction. Fibers can be placed in overlapping layers, toallow expansion in one plane only.

Adding fibers makes the bladder more puncture and tear resistant. Notethat the bladder can, for this purpose, also be made of or include aself-sealing material.

A third way of controlling expansion shape is to preshape the bladder toassume a certain form when expanded. This is done in the moldingprocess. The bladder is typically formed on a mandrel which is of aparticular shape and which is sized about half way between theunexpanded and the expanded size of the bladder.

The pre-determined shape of the unexpanded bladder is basically acombination of varying wall thickness and ribbing, made on a three partmold.

In certain experimental models constructed to date, the bladder isbonded onto a nylon stalk of 7 mm O.D. The bladder is stretched fromabout 3 mm to about 7 mm at its smallest dimension. This pre-stretchedarea puts the material under tension. Any larger diameter portions arerelaxed. As the bladder is expanded, the smaller diameter portion, whichis already partially expanded, stretches at a limited rate. The largerdiameter portion (under no load) expands at a faster rate. They balanceout at a point where all the material is under basically the same loadin tension. This is the point at which the shape is attained.

It should be understood that this particular example and its dimensionsare not limiting, and that any diameter can be used. This is an exampleof a specific sized cannula for a specific application.

With a typical material (silicone), the more you stretch the material,the more force is needed to stretch it further.

The prestretching of the bladder is done so that the bladder lies flaton the cannula body. The bonding areas are such that as the expansiontakes place the material expands radially outwardly as well as axially.

It can alternately be doubled up at a certain area, such as the tip of astalk or cannula. This will allow maximum expansion at the tip.

Tethering cords can be fixed to bladder portions and extend between themto control and/or limit the expansion of the bladder. This can be donewith bladders made of a composite material or including plates or otherthicker areas. In a cannula construct, the tethering cords can runbetween the cannula body to the crown of the bladder to control and/orlimit its expansion.

Plates can be added in which will limit the shape of the bladder orcreate an edge. For example, if a flat plate is added, the bladder canexpand in a circular fashion but the flat plate will remain flat andprovide a flat area on the outside of the bladder. Or the plate can becircular, or at an angle to create an edge. There can be multiple suchplates added to create specific shapes. Tethering cords can be used toextend to the plate. This can be useful in the cannula construct.

The bladder can also have a bellows-type construction for increasedexpansion control and structural rigidity.

Suction can be used to collapse any of the devices to facilitateremoval.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will becomeapparent to one skilled in the art upon a consideration of the followingdescription of the invention with reference to the accompanyingdrawings, wherein:

FIG. 1 is a side elevational view of a joint irrigation apparatus;

FIG. 2 is a longitudinal sectional view through the apparatus of FIG. 1;

FIG. 3 is a view taken along line 3—3 of FIG. 1;

FIG. 4 is a view of an alternate embodiment of the apparatus of FIG. 1;

FIG. 5 is a transverse sectional view through an expanding cannula;

FIG. 6 is a view of the cannula of FIG. 5 in an expanded condition;

FIGS. 7A and 7B illustrate a cannula having an outwardly expandingbladder formed within the wall of the cannula;

FIGS. 8A and 8B illustrate a cannula having an inwardly expandablebladder formed in the wall of the cannula;

FIGS. 9A and 9B illustrate a cannula having an inwardly and outwardlyexpanding bladder formed within the wall of the cannula;

FIGS. 10A, B and C illustrate the expansion of a cannula havingviscoelastic walls by means of an inserted inflatable member;

FIGS. 10-13 illustrate a cannula comprising a cylinder expandable alongits entire length;

FIG. 14 illustrates an elliptical or an oval-shaped cannula havingtethering cords;

FIG. 15 illustrates a square-shaped cannula having tethering cords;

FIG. 16 is a schematic view of a retractor shown in the unexpanded orcontracted and expanded or extended conditions;

FIG. 17 is a schematic view of a retractor extending through a cannulaand mounted on the end of a separate shaft;

FIG. 18 is a schematic view similar to FIG. 17 illustrating the use of afiber optic scope with the retractor;

FIG. 19 is a schematic view showing a retractor inserted through aseparate side opening in a cannula;

FIGS. 20A-E are schematic views of a few of the many and various shapesin which the inflatable portion of the retractor may be formed;

FIG. 21 is a schematic view of a retractor shown mounted on the end of acannula and having an opening therein for a scope to pass through;

FIG. 22 is a diagram of a fluid supply system for operating a retractor;

FIG. 23 is a view illustrating the use of a retractor to position theend of a scope;

FIG. 24 is a view similar to FIG. 23 further illustrating the use of aretractor to position the end of a scope;

FIG. 25 illustrates a cannula having a tethering cord connecting aballoon portion to the cannula wall;

FIG. 26 is a sectional view illustrating a continuous mass of bodytissue which is free of an opening;

FIG. 27 is a schematic illustration depicting the manner in which thecannula of FIG. 25 is inserted into the mass of body tissue of FIG. 26and expanded to form an open space in the mass of body tissue at alocation adjacent to and axially outward from a distal end of thecannula;

FIG. 28 is an enlarged view of the cannula of FIG. 27 and illustratingthe manner in which a fiberoptic scope and a tool are insertedthrough-the cannula into the space formed in the body tissue at alocation axially outward from the distal end of the cannula by expandingthe cannula;

FIG. 29 is an enlarged fragmentary sectional view of a cannula having aflexible wall and tethers, the flexible wall being shown in a retractedcondition;

FIG. 30 is a fragmentary sectional view, generally similar to FIG. 29,illustrating the flexible wall in an extended condition with a tetherlimiting outward movement of a portion of the flexible wall;

FIG. 31 is a fragmentary sectional distal end view, taken generallyalong the line 31—31 of FIG. 30, illustrating the manner in which aplurality of tethers extend outwardly from a main section of the cannulatoward the flexible wall;

FIG. 32 is a fragmentary schematic plan view of a portion of a side wallof the flexible wall of the cannula of FIGS. 29-31 and schematicallyillustrating the relationship between reinforcing fibers in a proximalportion of the side wall;

FIG. 33 is a fragmentary plan view of another portion of the side wallof the flexible wall of the cannula of FIGS. 29-31 and schematicallyillustrating the relationship between reinforcing fibers in a distalportion of the flexible wall;

FIG. 34 is a plan view of a portion of an end wall of the flexible wallof FIGS. 29-31 and schematically illustrating the relationship betweenreinforcing fibers in the end wall;

FIG. 35 illustrates a cannula which is selectively expandable at one ormore selected longitudinal locations;

FIGS. 36 and 37 illustrate a cannula having a plurality ofcircumferentially spaced expandable segments;

FIGS. 38-43 illustrate longitudinally extending radially expansiblecannula segments;

FIGS. 44 and 45 illustrate expandable devices having textured surfaces;

FIGS. 46-49 illustrate a cannula having an expandable bladder portionwith a varying wall thickness;

FIGS. 50-52 illustrate flexible bladder portions having relatively rigidmembers molded therein;

FIGS. 53 and 54 illustrate rigid members molded into the elastomericmaterial of an inflatable bladder circumscribing a cannula or othermedical device;

FIGS. 55 and 56 illustrate a cannula having a bladder with adoubled-over bladder portion;

FIG. 57 is a schematic illustration of a cannula having the same generalconstruction as the cannula of FIGS. 55 and 56, the cannula of FIG. 57having tethers and being shown in a retracted condition;

FIG. 58 is a schematic illustration of the cannula of FIG. 57 in anextended condition with the tethers restraining movement of a flexiblewall portion of the cannula;

FIG. 59 is a schematic illustration of a cannula having the same generalconstruction as the cannula of FIG. 58, the cannula of FIG. 59 having aplurality of tethers disposed within a chamber formed by the expandedflexible wall of the cannula;

FIG. 60 is an end view, taken generally along the line 60—60 of FIG. 59,illustrating the manner in which a plurality of tethers are connectedwith the flexible wall of the cannula;

FIG. 61 is a sectional view, taken generally along the line 61—61 ofFIG. 59, illustrating the manner in which a plurality of tethers extendoutwardly from a main section of the cannula toward an inner sidesurface of the flexible wall of the cannula;

FIG. 62 is a sectional view, taken generally along the line 6-2-62 ofFIG. 59, illustrating the manner in which a plurality of tethers extendoutwardly from a main section of the cannula towards the inner sidesurface of the flexible wall;

FIG. 63 illustrates an expanded bladder having adjoining portions withdifferent material characteristics;

FIG. 64 illustrates an expanding device having an expanding bladder madeof a plurality of materials laminated together;

FIGS. 65A-65C illustrate triangular-shaped expanding portions;

FIGS. 66A-66C illustrate trapezoidal-shaped expanding portions;

FIGS. 67A-67C illustrate the use of overlapping and/or incomplete fibersfor expansion control;

FIGS. 68-76 illustrate a variety of bladder devices includingreinforcing fibers and/or tethering cords; and FIGS. 77-79 illustrate astructural unit comprising a series of expandable bladders laminatedtogether.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1-3 illustrate an arthritis irrigation apparatus 10. Theirrigation system 10 includes a cannula 12 having a disc portion 14 anda longitudinally extending cannula body 16. A central wall 18 dividesthe cannula body 16 into two longitudinally extending lumens 20 and 22.

An expandable bladder 30 is connected to or formed integrally with thecannula 12 at the distal end 32 and proximal end 34 of the cannula body16. The expandable bladder 30 includes a longitudinally extending wallportion 36 and a transversely extending wall portion 38. The expandablebladder 30 is supplied with fluid under pressure through a fluid supplyport 40 closed by a rubber diaphragm seal 42. The lumens 20 and 22 areclosed by similar diaphragm seals 44 and 46, respectively. The cannulabody 16 has a recessed portion 48 in which the bladder 36 fits whenunexpanded.

The system 10 is inserted into a pre-made opening until the disc portion14 engages the skin. Upon the introduction of fluid under pressure intothe expandable bladder 30, the bladder 30 expands from the unexpandedcondition illustrated in FIG. 1 to the expanded condition illustrated inFIG. 2. The bladder wall 36 moves radially outwardly, and skin or othertissue is trapped between the bladder wall 38 and the distal surface 49of the disc portion 14 of the cannula 12.

The system 10 is thus locked in place, with the distal end 32 inposition in a joint. Appropriate instruments may then be insertedthrough the diaphragm seals 44 and 46 into the lumens 20 and 22,respectively. For example, flushing fluid may be supplied to the jointthrough the lumen 20, while it is removed from the joint by suctionthrough the lumen 22. When the joint is not being flushed, the diaphragmseals 42, 44 and 46 seal the openings in the system-10, and the expandedbladder 30 retain3 the system 10 in place in the body.

It should be understood that any number of lumens, other than two, canbe included in the cannula body 16. The number of lumens is limited onlyby the size of the instruments to be inserted through the cannula body16. In a preferred embodiment, the disc portion 14 of the cannula body12 is about the size of a nickel, with the cannula body 16 beingcorrespondingly smaller. Of course, the dimensions and arrangement ofthe various portions of the system 10 could be modified to enable theplacement of other instruments through the cannula body 16.

Each of the lumens may have a controllable inflow-outflow portal. Thesecan be substituted for the diaphragm seals. These portals may be asimple tube with an on-off valve attached, as is known in the art, orcan be another suitable structure.

FIG. 4 illustrates an alternate embodiment of the system 10 in which asystem 50 includes a round or doughnut-shaped bladder 52 extendingbetween the distal end 32 and the proximal end 34 of the cannula wall16. This doughnut-shaped bladder can be easier or less expensive tomanufacture, and also can provide more cushioning effect to the tissueswhich it engages. Again, tissue is trapped between the bladder 52 andthe disc portion 14 of the cannula 12, to retain the system 50 in placein the body.

FIGS. 5 and 6 illustrate a variable size cannula in which inflatablebladders push apart two relatively rigid portions to move tissue. FIGS.5 and 6 are transverse cross sections through a longitudinally extendingcannula 60, which can be any desired length. The cannula 60 expandsradially outwardly along its length.

The cannula 60 includes a first C-shaped portion 62 having ends 64 and66 and a second C-shaped portion 68 having ends 70 and 72. An inflatablebladder 74 has one end portion 76 fixed to the end portion 64 of theportion 62. The opposite end portion 78 of the bladder 74 is fixed tothe end portion 70 of the portion 68. Similarly, a bladder 80 has oneend portion 82 fixed to the end portion 66 of the portion 62, and itssecond end portion 84 fixed to the end portion 72 of the portion 68.

The portion 62 has an outwardly facing surface 86 and the portion 68 hasan outwardly facing surface 88. The cannula 60 has a central opening 90which is enlarged in size upon expansion of the bladders 74 and 80 toprovide a larger working space while reducing tissue damage. Upon theintroduction of fluid under pressure into the bladders 74 and 80, theportions 62 and 68 are moved away from each other to engage tissue withtheir surfaces 86 and 88, respectively. The relatively rigid portions 62and 68 provide increased pushing strength of the cannula 60 as comparedto a soft inflatable bladder. Further, the cannula 60 also holds itsstructural shape better and is able to maintain the opening better.Thus, with the cannula 60, a limited incision can be made in the tissue,which incision is then enlarged by the cannula itself rather than with acutting device. The application of suction to the bladders 74 and 80causes them to deflate to return the cannula 60 to its unexpandedcondition. The tissue is viscoelastic and thus will stretch out duringits expansion by the expander 60, and then return to its originalunexpanded shape, i.e., the original size of the incision after removalof the cannula. Thus, less tissue damage results.

Cannulas in accordance with the present invention may have one or morebladders as part of the cannula wall., These may create inward oroutward expansion. For example, FIGS. 7A and 7B illustrate alongitudinal portion of a cannula 92 having a wall portion 94 defining acentral opening 96 through which surgical instruments or the like can bepassed. The wall portion 94 includes a portion 98 partially defining afluid chamber 100 which may be supplied with fluid under pressurethrough a fluid supply line 102 extending through the cannula wall 94.On the introduction of fluid under pressure into the volume 140, thewall portion 98 of the cannula 92 expands radially outwardly, from theunexpanded condition of FIG. 7B to the expanded condition of FIG. 7A, asa seal or retainer against tissue.

Similarly, the cannula 104 illustrated in FIGS. 8A and 8B includes awall 106 having an inner portion 108 defining a fluid volume 110. Uponthe introduction of fluid under pressure through a supply passage 112 inthe wall 106, the wall portion 108 expands radially inwardly to close atleast partially the central opening 113 in the cannula 104. Theexpanding portion 114 of the cannula 104 thus acts as a valve or sealfor the central opening 110 of the cannula. This can be very useful ifit is desired to close the central opening 110 while leaving the cannula104 in place in the body tissue. The central passage 113 can also beclosed completely. Alternatively, the wall portion 108 can clamp onto aninstrument or scope extending through the passage 113 to lock it inplace.

In addition to the cannula inner seals or valves formed by the radiallyinwardly expanding bladder walls, the present invention contemplatescannula inner seals formed by other structures. For example, a simplemechanical seal can be used such as a diaphragm seal like the seals 44and 46 (FIGS. 1-3). Other forms of mechanical seals can be used, such asa membrane (iris) valve, screw lock, twist lock, or luer lock. It isintended that these alternatives be included within the scope of theinvention.

FIGS. 9A and 9B illustrate a cannula 116 having an expanding portion 118in its wall 120. Upon the introduction of fluid under pressure through afluid supply passage 122 in the wall 120, a portion 124 of the cannulawall 120 expands radially outwardly while a longitudinally coextensiveportion 126 of the wall 120 expands radially inwardly to partially orcompletely close a central longitudinally extending passage 128. Thus,the cannula 116 has a portion 118 which expands both inwardly andoutwardly. The cannulas of FIGS. 7-9 thus illustrate the principle ofexpanding either inward or outward or both at selected axial locationsalong the longitudinal extent of a cannula.

FIGS. 11A-10C illustrate the expansion of a stretchable cannula by anexpandable member inserted therein. A cannula 130 has a wall 132defining a central longitudinally extending passage 134. The cannula 130is made of a stretchable material having viscoelastic properties wherebythe wall 130 when stretched outwardly will retain its stretchedcondition for a period of time. An expander 136 includes a stalk 138 onthe end of which is mounted an expanding portion 140. Upon insertion ofthe expander 136 into the cannula 130 as illustrated in FIG. 10S, theexpanding portion 140 may be expanded radially outwardly by theintroduction of fluid under pressure through the stalk 138, to stretch awall portion 142 of the cannula wall 132 radially outwardly. Uponsubsequent deflation of the expanding portion 140 of the expander 136,and removal of the expander 136 from the cannula 130, the cannula wallportion 142 remains in its stretched condition for at least a period oftime. The cannula 130 is thereby retained in place in the surroundingtissues while instruments or a scope can be passed through it.

The present invention contemplates monitoring the pressure applied totissue by the expanding cannula. This can be done, for example, with anyknown pressure sensor or strain gauge. Such is indicated schematicallyat 144 in FIG. 10C as being on the wall of the device 136 used tostretch the cannula 130. Alternatively, it is indicated schematically at146 in FIG. 10C as being on the wall of the cannula 130.

FIGS. 11-13 illustrate a cannula. 150 which comprises a cylinderexpandable along its entire length. The cannula 150 has a centrallongitudinally extending working passage 152 defined by an inner wall154. An inflation space 156 separates the inner wall 154 from an outerwall 158 of the cannula 150. A series of tethering cords 160 extendbetween the inner wall 154 and the outer wall 158.

The inner and outer walls 154 and 158, respectively, of the cannula 150are constructed so that, upon the introduction of fluid under pressureinto the inflation space 156, both walls expand radially outwardly to alarger diameter. Fluid is introduced through a fluid inflow means (notshown) which may be a simple tube or valve in fluid communication withthe inflation space 156. The cannula 150 expands from the conditionshown in FIG. 12 to a further expanded condition as illustrated in FIG.13. The tethering cords 160 limit movement of the outer wall 158 of thecannula 150 from the inner wall 154 of the cannula 150. In a preferredembodiment, the tethering cords 160 comprise fibers (either solid orstranded) having their ends fixed to the inner wall 154 and the outerwall 158 and extending therebetween. The tethering cords 160 may beunextensible, or they may be somewhat extensible upon the application ofa relatively large amount of force. Use of the tethering cords 160 isadvantageous in that it allows for controlled expansion of spacedportions of an inflatable device.

The cannula 150 is circular in cross sectional shape. It should beunderstood that the present invention is not limited to circularcannulas, but specifically contemplates the provision of cannulas of anytype described herein of other cross sectional-shapes. The crosssectional shape of a particular cannula may be selected in accordancewith a particular application for that cannula. For example, anelliptical or oval-shaped cannula 162 (FIG. 14) may be more suitable forinsertion between adjacent tissue planes, as it conforms more to theopening between the tissue points. The oval-shaped cannula 162 includesan outer wall 164, an inflation space 166, an inner wall 168, and aworking passage 170 extending axially therethrough. Optionally aplurality of tethering cords 172 extend between the inner wall 168 andthe outer wall 164, and limit movement of the outer wall 164 from theinner wall 168.

FIG. 15 illustrates, as exemplary of the other shapes of cannulas whichmay be provided, a rectangular (in this case square) shaped cannula 174optionally having a plurality of tethering cords 176 extending betweenthe outer cannula wall 178 and an inner cannula wall 180. The inner wall180 defines a working passage 182 extending longitudinally through thecannula 174.

FIG. 16 illustrates schematically a retractor 510 in accordance with thepresent invention. The retractor 510 includes a fluid supply structure512 and an expandable balloon or bladder 514 having a flexible walllocated at or near the end of the structure 512. The bladder isexpandable, under the force of fluid under pressure, from an unexpandedor retracted condition as indicated in full lines at 514 to an expandedor extended condition as shown in broken lines at 516. In the expandedcondition, the transverse dimension 518 of the bladder 514 issignificantly greater than its transverse dimension before expansion,that is, the dimension 520. Also, in the expanded condition, thetransverse dimension 518 of the bladder 514 is significantly greaterthan its longitudinal dimension 520.

When the bladder of the retractor is expanded inside the body, itretracts tissue. As seen in FIG. 17, a bladder 522 is mounted on the endof a separate shaft 524 within a cannula or scope 526. The cannula orscope 526 has been inserted into the body through an opening 528 in theskin (either pre-existing or made in situ) which has a transversedimension 530. The bladder 522 when in its unexpanded condition as shownin broken line is smaller than the dimension 530 of the body opening,but when expanded, it expands to a dimension 532 which is significantlygreater than the dimension 530. An actual space or working space 534 isformed which was not present before the expansion of the bladder.

The newly-formed working space may be used, for example, for better useof a fiber optic scope as illustrated in FIG. 3. In FIG. 18, a retractor510 is passed through an opening 536 in a cannula 538. A fiber opticscope shown schematically at 540 is also passed through the cannula 538.The cannula 538 is inserted into the body through an opening in the bodytissues 5 t 2 which is only as large as the outer diameter of thecannula 538. The retractor 510 is then inflated, with air or anotherfluid being supplied through a rigid or flexible shaft 544 to anexpandable bladder 546. The bladder 546 expands transversely, retractingthe tissues 542 transversely and creating a working space 534. By axialmanipulation of the shaft 544, the bladder 546 is movable either towardthe end of the scope 540 in the direction as indicated by the arrow 548,or away from the end of the scope 540 as indicated by the arrow 550, asdesired. Such manipulation of the retractor can selectively move andplace the adjoining body tissues where the surgeon wants them to enablebetter use of the scope 540 by the surgeon.

As shown in FIG. 19, the retractor 510 may be inserted into a cannula552 through a separate opening 554 therein. The opening 554 is shown onthe side of the cannula 552, although, of course, it may be on the endof the cannula as is typical. Alternatively, the retractor 510 may beinserted into the body through an opening in the body tissues separatefrom the opening through which the fiber optic scope is inserted. Eitherof these options allows for greater flexibility in the insertion andpositioning of the retractor 510 relative to the other instruments beingused such as the arthroscope.

Also as indicated in FIG. 19, the bladder 558 may be eccentric oreccentrically located relative to the opening 560 at the junctionbetween the bladder 558 and the shaft 562. This is accomplished by usingknown techniques to form the bladder 558 of a material, construction,and shape such that it expands into the eccentric shape as illustratedin FIG. 19 when inflated by fluid under pressure through the shaft 562.In this manner, an improved visualization and working space 534 iscreated which is eccentrically located relative to the other instrumentsbeing used. This may be preferable when the surgeon is using an angledscope.

FIG. 19 is illustrative of the fact that the bladder of the retractor ofthe present invention may be formed so as to expand into any particularshape as desired for the particular application. This feature is alsoshown schematically in FIGS. 20A through 20E which illustrate,respectively, retractor bladders which assume in their expanded statesin round, oval, eccentric, oblong, and conical shapes. Such shapes maygenerally be called “nonuniform” shapes for purposes of the presentinvention, and refractors with such a shape will expand in a“non-uniform” manner. Such shapes may include, for example, wedge- orU-shaped filaments which collapse at the skin, then expand at deeptissue planes for visualization and working space. The bladder may alsocup and protect vital tissues such as nerves and arteries while workingon other tissues such as muscle.

Another typical form of construction is illustrated in FIG. 21, whichshows a bladder 564 which in its expanded condition assumes a toroidalshape. Again, the width 566 of the bladder 564 is significantly greaterthan its length 568. The bladder 568 is expanded by fluid under pressurereceived through a fluid channel 570 formed between a cannula or scopeouter wall 572 and inner wall 573. By virtue of the toroidal shape ofthe bladder 568, the leading end 574 of the scope 576 may be passedaxially completely through the retractor into the working space 534which has been created in the tissues 578. Such a bladder 564 may alsobe mounted on a separate shaft inserted through the scope of thecannula.

In all cases, the fluid pressure within the bladder of the retractor ismonitored and controlled to keep the force exerted by the retractor at asafe level for tissue to prevent tissue necrosis. As indicatedschematically in FIG. 22, a retractor 510 is supplied with fluid underpressure from a fluid pressure source 580 via a fluid supply line 582. Aregulator 584 controls the supply of fluid to the retractor 510. Apressure sensor 586 is located within the retractor 510 and senses thepressure of the fluid within the retractor 510. The pressure sensor 586sends a signal which is representative of the fluid pressure within theretractor 510, via wiring 588, to a monitor 590. The monitor 590 isconnected via control wiring 592 to the pressure regulator 584. Thepressure of the fluid within the retractor 510 may thus be monitored andcontrolled either manually or automatically, by means which are wellknown in the art and so need not be described further herein. The source580 of fluid supply may be, for example, the air pressure supply whichis commonly found in hospital operating rooms.

By virtue of this ability to monitor the pressure within the retractor510, the retractor 510 can also be a useful diagnostic tool. Thestrength or pressure or resistance of tissue to movement can be measuredby the pressure required to move it.

FIGS. 23 and 24 illustrate the use of a retractor of the presentinvention to stabilize a fiber optic scope. The retractor 510 (FIG. 23)includes a bladder 594 which retracts the body tissues 596 away from thescope 598.

Since the bladder 594 engages and pushes radially outwardly on bodytissues 596 all around the scope 598, the retractor becomes fixed inposition when it is so expanded. If the bladder 594 is fixed to the endof the scope 598, the retractor 510 thereby fixes the end of the scope598 in position relative to the body tissues 596. When a camera is beingused with the scope 598, the picture normally moves or jumps aroundbecause of the movability of the end of the scope 598. This is preventedby so using the retractor 510 to stabilize the scope 598, leaving thesurgeon with both hands free to work and a steady view of the work area.

FIGS. 23 and 24 also illustrate how the retractor of the presentinvention can be used to control the placement of the tip of a fiberoptic scope. The retractor 510 is formed with an eccentric bladder 594which retracts the body tissues 596 away from the scope 598 to a greaterdistance in one direction than in another. Thus, by rotating theretractor 510, the surgeon can place the tip of the scope 596 closer tothe body tissue 599 (FIG. 23) on one side of the working space 534, orto the body tissue 597 (FIG. 24) on the other side of the working space534. Such variable placement can, of course, also be attained via use ofa retractor 510 which includes a bladder which can be expanded tovarying shapes.

The retractor of the present invention has many uses in the surgicalfield. The retractor 510 can be used to retract soft tissue from bone,for example within a joint The retractor 510 is inserted between thebone and the soft tissue 112. The bladder 594 is then expanded. The softtissue is forced away from the bone. The surgeon may then use a fiberoptic scope or other instrument to work within the working space createdby the retractor 510. The retractor of the present invention can providethe force needed to move the soft tissue away from the bone may varybetween about 100 and 1000 mm Hg, and thus, it is important to maintainthe proper pressure between the two. The retractor 510 can do this sinceit operates on high fluid pressures of about 10 to 1000 mm Hg and itutilizes a high strength material such as Kevlar, Mylar, or anotherdurable polymer such as Polylite®, a product of Reichhold Chemicals,Inc. This simple retraction of soft tissue from bone would otherwise beimpossible.

FIG. 25 illustrates the use of a tethering cord to position a bladderportion relative to a cannula wall. A cannula 190 has a main sectionwith an outer wall 192 and an-inner wall 194 spaced therefrom. The wall194 divides the interior of the cannula 190 into a working passage 196and an inflation fluid passage 198. The passage 198 opens into a bladderor flexible wall 200 fixed at the distal end 202 of the cannula 190.Tethering cords 204 extend between the cannula wall 192 and a junctionor crown 206 of the bladder or flexible wall 200. The tethering cords204 limit movement of the crown portion 206 of the bladder or flexiblewall 200 from the cannula wall 192.

The cannula 190 of FIG. 25 is only illustrative of the many ways inwhich bladder portions can be positioned relative to cannula portions bytethering cords such as the tethering cord 204. The number andpositioning and length of the tethering cords determines the relativemovement of the various bladder portions to which they are attached,thus aiding in controlling the expanded shape of the bladder relative tothe cannula.

The cannula 190 can be used to create an open space in a continuous massof body tissue. Thus, a continuous mass 207 (FIG. 26) of body tissue isfree of naturally occurring openings. The mass 207 of body tissue isenclosed by skin 208. The skin 208, like the mass 207 of body tissue, isfree of naturally occurring openings.

A small slit or incision 209 (FIG. 27) is formed by a surgeon in theskin 208. The cannula 190 is then inserted through the slit 209 in theskin 208. At this time, the bladder 200 in a retracted condition inwhich it is tightly disposed against the outer wall or main section 192of the cannula.

Once the cannula 190 has been inserted through the slit 209 and movedinto the mass 207 of body tissue, the bladder or flexible wall 200 ismoved from the retracted condition to an extended condition. This isaccomplished by a conducting fluid pressure through the passage 198 intothe flexible wall 200. The fluid pressure expands the flexible wall 200from a contracted condition to an extended condition.

As the flexible wall 200 is extended, a portion 211 of the mass 207 ofbody tissue is moved outward away from the outer wall 192 of the mainsection of the cannula 190. Thus, as the flexible wall 200 is inflated,an outer side surface of the flexible wall presses against the portion211 of the mass 207 of body tissue, in the manner indicatedschematically by arrows in FIG. 27. This pressure moves at least part ofthe portion 211 of the mass 207 of body tissue toward the left (asviewed in FIG. 27). As this occurs, force is transmitted from theportion 211 of the mass of body tissue to a portion 213 (FIG. 27) of themass 207 of body tissue.

The force transmitted through the mass 207 of body tissue to the portion213 of the body tissue moves the portion 213 of the body tissue awayfrom the distal or axially outer end 202 of the cannula 190. As thisoccurs, an open space 215 is formed at a location in the mass 207 ofbody tissue where there was no space prior to insertion of the cannula190 and expansion of the flexible wall 200.

The portion 213 of the mass 207 of body tissue is moved away from thedistal end 202 of the cannula 190 under the influence of force which istransmitted through the mass of body tissue from the portion 211 of thebody tissue to the portion 213 of the mass of body tissue. Thus, theouter side surface of the flexible wall 200 is effective to apply force,in the manner indicated by arrows in FIG. 27, against only the portion211 of the mass 207 of body tissue. Force is transmitted by body tissuefrom the portion 211 of the mass of body tissue to the portion 213 ofthe mass 207 of body tissue. The force transmitted through the bodytissue moves the portion 213 of the mass 207 of body tissue away fromthe distal end 202 of the cannula 190 and thereby create the open space215 in the mass 207 of body tissue.

Creation of the open space 215 in the mass of body tissue provides aviewing area adjacent to the distal end 202 of the cannula-190 for asurgeon to operate. Thus, a endoscope 217 and an operating tool 219 canbe inserted through the passage 196 in the cannula 190. The outer ordistal ends of the endoscope 217 and operating tool 219 project beyondthe distal end 202 of the cannula 190 into the open space 215. Thisenables a surgeon to view the distal end of the operating tool 219through the endoscope 217 and to view the portion of the mass 207 ofbody tissue which is to be operated on with the tool 219. Of course,since the surgeon can view the operations being performed by the tool219, the work of the surgeon on the body tissue 207 is greatlyfacilitated.

The flexible wall or bladder 200 of the cannula 190 (FIG. 28) includes aside wall 191 and an end wall 193 which are formed of an elastomericmaterial. When the cannula 190 is inserted through the incision 209, thenatural resilience of the elastic end wall 193 and elastic side wall 191causes the bladder or flexible wall 200 to tightly enclose the outerwall 192 of the cannula 190. This results in the tethers 204 beingenclosed by the bladder or flexible wall 200 and being pressed againstthe outer wall 192 of the cannula 190.

After the cannula 190 has been inserted through the incision 209 andmoved into the continuous mass 207 of body tissue, the bladder 200 isinflated to cause the elastic side wall 191 and end wall 193 of thebladder 200 to move outward to the extended condition shown in FIG. 28.A radially and axially inner end 195 of the side wall 191 of the bladder200 is bonded to the outer side surface of the outer wall 192 of thecannula 190. A radially inner end of the end wall 193 is bonded at 197to the outer side surface of the outer wall 192 of the cannula 190. Anopening for the fluid passage 198 extends through the outer wall 192 ata location between the connection 195 of the side wall 191 with theouter wall 192 of the cannula 190 and the connection 197 of the end wall193 with the outer wall 192 of the cannula.

When the bladder or flexible wall 200 (FIG. 28) is to be inflated fromthe retracted condition to the extended condition shown in FIG. 28,fluid pressure is conducted through the passage 198 into the bladder200. As the fluid pressure flows into the bladder 200, an annularchamber 199 is established around the outer wall 192 of the cannula 190.As this occurs, the side wall 191 of the bladder 200 presses body tissueradially outward and axially away from the distal end 202 of the cannula190 in the manner indicated by the arrows in FIG. 27. As this isoccurring, the body tissue extends axially outward from the junction 206between the side wall 191 and end wall 193 of the bladder or flexiblewall 200. The body tissue which extends outward from the junction orcrown 206 of the bladder 200 is tensioned and tends to continue outwardfrom the junction. Due to the fact that the end wall 193 extendsradially outward from the cylindrical outer wall 192 of the cannula 190,an opening is formed immediately axially outward from the end wall 193as the bladder 200 is inflated.

As the bladder 200 is inflated, the tether cords 204 are extended from anonlinear configuration toward the linear configuration illustrated inFIG. 28. When the bladder or flexible wall 200 reaches the fullyinflated condition shown in FIG. 28, an inflated structure is formed.The tether cords 204 restrain the junction between the side wall 191 and193 from moving further radially outward. This results in the elasticside wall 191 having a configuration corresponding to the configurationof a portion of a cone and the elastic end wall 193 having aconfiguration corresponding to the configuration of a flat annular disk.The side wall 191 and end wall 193 are initially formed to thisconfiguration while they are in a stretched condition over a formingtool. The tethering cords 204 cooperate with the side wall 191 and endwall 193 to ensure that the inflated structure formed by the bladder 200has the configuration illustrated in FIG. 28.

The body tissue 207 which is pressed radially outwardly and axially awayfrom the distal end 202 of the cannula 190 by movement of the bladder200 from the retracted condition to the expanded condition shown in FIG.28 causes the body tissue to move away from the end wall 193 as thebladder is inflated. This results in the formation of the open space 215axially outwardly from the end wall 193. Thus, the portion 211 of thebody tissue disposed to the left (as viewed in FIG. 28) of the inflatedbladder or flexible wall 200 pulls or tensions the portion of the bodytissue which extends across the circular crown portion or junction 206.The forces transmitted through the body tissue itself tends to pull thebody tissue away from the end wall 193 to form the open space 215 in themanner illustrated in FIG. 28.

A cannula 600 (FIGS. 29 and 30) has the same general construction as thecannula 190 of FIGS. 25-28. The cannula 600 includes a tubular mainsection 601 having a cylindrical outer wall 602 which extends from aproximal end portion (not shown) of the cannula 600 to a distal endportion 604 of the cannula. A flexible wall or bladder 606 is connectedwith the wall 602 of the main section 601.

The-flexible wall 606 has a proximal end portion 607 which is bonded toan annular shoulder 608 formed in the wall 602. A cylindrical clamp ring609 also secures the proximal end portion 607 to the wall 602 of themain section 601 of the cannula 600.

A distal end portion 610 of the flexible wall 606 is connected to thedistal end of the main section 601 of the, cannula 600. In theillustrated embodiment of the invention, the distal end portion 610 ofthe flexible wall is bonded to the distal end of the main section 601 ofthe cannula 600. However, the distal end portion 610 of the flexiblewall 606 could be connected to the distal end of the-main section 601 inother ways such as by the use of a mechanical retainer. When theflexible wall 606 is in the initial or retracted condition shown in FIG.29, the flexible wall tightly adheres to the main section 601 of thecannula 600 to provide a smooth outer surface which has a minimum ofinterference with body tissue as the cannula 600 is inserted into acontinuous mass of body tissue.

An inner wall 612 cooperates with the wall 602 to form a passage 614 forfluid. The passage 614 has a proximal end (not shown) at which fluidunder pressure is conducted into the passage. The passage 614 has aplurality of circular distal openings 616 through which fluid can flowfrom the passage 614 to a space enclosed by the flexible wall 606.

When the flexible wall 606 is to be inflated, fluid pressure flowsthrough the passage 614 and opening 616 and is applied against an innerside surface 617 (FIG. 29) of the flexible wall. The fluid pressureapplied against the inner side surface 617 of the flexible wall 606causes the flexible wall to move from the retracted condition shown inFIG. 29 toward the fully extended condition shown in FIG. 30. As thisoccurs, a plurality of tether cords 618 are pulled from a nonlinear orcoiled configuration toward the linear configuration shown-in FIGS. 30and 31.

When the flexible wall 606 is in the retracted condition shown in FIG.29, the flexible wall covers the tethers 618 and presses them firmlyagainst the tubular wall 602 of the main section 601 of the cannula 600.Since the tethers 618 are enclosed by the flexible wall 606, they do notinterfere with insertion of the cannula 600 into a continuous mass ofbody tissue 207 where an opening does not naturally occur. Therelatively high pressure fluid conducted from the passage 614 throughthe openings 616 move the flexible wall 606 outwardly away from the mainsection 601 of the cannula 600 to initiate the formation of an inflationfluid chamber 620. As this occurs, the flexible wall 606 forms aninflated structure 622.

The inflated structure 622 has a side wall 624 and an end wall 626. Theside wall 624 and end wall 626 are connected at a circular junction 628.The side wall 624 has a configuration corresponding to the configurationof a portion of a cone while the end wall 626 has a configurationcorresponding to the configuration of a flat annular disk when theflexible wall 606 is in the fully extended position of FIG. 30. Thetethering cords 618 limit outward movement of the junction 628 betweenthe side wall 624 and the end wall 626 to impart the desiredconfiguration to the inflated structure 622.

Each of the tethering cords 618 has an outer end portion which issecured to the inner side surface 617 of the flexible wall 606 at thejunction 628. In the illustrated embodiment of the invention, thetethering cords 618 are bonded to the elastomeric material forming theflexible wall 606. However, it is contemplated that the tethering cords618 could be connected with the flexible wall 606 in many differentways. The inner end portions of the tethers 618 are bonded to the mainsection 601 of the cannula 600. The inner end portions of the tethers618 could be secured to the main section 601 of the cannula 600 in manydifferent ways other than bonding.

The tethering cords 618 limit radially outward movement of the junction628 between the end wall 626 and side wall 624. By limiting outwardradial movement of the end wall 626 and the side wall 624, the tetheringcords 618 restrain the elastic material of the flexible wall 606. Thisresults in the inflated structure 622 having a configuration whichcorresponds to the configuration of a portion of a cone.

Once the flexible wall 606 has been moved to the extended condition ofFIG. 30, instruments, such as an endoscope and/or operating tools, canbe inserted through a cylindrical central opening 630 (FIG. 31) formedin the main section 601 (FIGS. 29 and 30) of the cannula 600. Inaddition to the tethers 618, reinforcing fibers 632 (FIGS. 32, 33 and34) are utilized to impart the desired configuration to the inflatedstructure 622.

A portion of the reinforcing fibers 632 is disposed in the side wall 624(FIGS. 32 and 33) of the inflated structure 622. Another portion of thereinforcing fibers 632 is disposed in the end wall 626 of the inflatedstructure 622. The reinforcing fibers 632 cooperate with the elastomericmaterial, which may be silicone, or latex, to restrain the elastomericmaterial of the flexible wall 606 against excessive stretching under theinfluence of fluid pressure applied against the inner side surface 617(FIGS. 30 and 31) of the flexible wall 606.

In the illustrated embodiment of the invention, the inflated structure622 has a configuration corresponding to the configuration of a portionof a cone. Therefore, a proximal portion 607 of the side wall 604 has asmaller diameter than a distal end portion 633 of the side wall 624. Thedensity of reinforcing fibers 632 in the proximal end portion 607 (FIG.32) of the side wall 624 is greater than the density of reinforcingfibers 632 in the distal portion 633 of the side wall 624. By having thereinforcing fibers in the proximal end portion 607 (FIG. 32) of-the sidewall 624 closer together, the reinforcing fibers are effective to limitoutward radial expansion of the proximal portion 607 of the side wall624. The relatively widely spaced reinforcing fibers 632 (FIG. 23) inthe distal end portion 633 of the side wall 624 allow the distal endportion 633 of the side wall 624 to expand radially outwardly to agreater extent than the proximal end portion 607 of the side wall 624.

The reinforcing fibers 632 in the proximal end portion 607 of the sidewall 624 (FIG. 32) include fibers 634 having longitudinal axes whichextend generally parallel to a longitudinal 110 central axis of the mainsection 601 of the cannula 600. In addition, reinforcing fibers 635extend circumferentially around the distal portion 607 of the side wall624. The reinforcing fibers 635 have longitudinal axes which extendgenerally perpendicular to the longitudinal axis of the reinforcingfibers 634. The longitudinal extending fibers 634 and thecircumferentially extending fibers 635 reinforce the proximal portion607 of the side wall 624 to limit the extent to which the fluid pressureapplied against the inner side surface 617 of the side wall is effectiveto stretch the elastomeric material of the flexible wall 606.

Similarly, the distal end portion 633 (FIG. 33) of the side wall 624 haslongitudinally extending fibers 636 having longitudinal axes whichextend parallel to the longitudinal central axis of the main section 601of the cannula 600. The reinforcing fibers 632 in the distal end portion633 of the side wall 624 also include circumferentially extending fibers637 which are perpendicular to the longitudinally extending fibers 636.The reinforcing fibers 632 in the distal portion of the side wall 624are far more widely spaced than the reinforcing fibers in the proximalend portion 607 of the side wall 624. This enables the elastomericmaterial of the distal end portion 633 to stretch under the influence offluid pressure applied against the inner side surface 617 (FIG. 30) ofthe side wall 624. Therefore, the distal portion 633 of the side wall624 stretches to have a substantially greater diameter than the proximalportion 607 of the side wall 624.

The reinforcing fibers 632 in the end wall 626 (FIG. 34) include fibers638 which extend radially outwardly from the cylindrical passage 630through the main section 601 of the cannula. Circumferentially extendingfibers 639 cooperate with the radially extending fibers 638 to limit theexpansion of the end wall 626 under the influence of fluid pressureapplied against the inner side surface 617 of the flexible wall 606.During formation of the flexible wall 606, the elastomeric material ofthe flexible wall is configured to have a configuration corresponding tothe desired, generally conical, configuration of the inflated structure622 (FIG. 30).

The cannula 600 is inserted into a continuous mass of body tissue,corresponding to the continuous mass 207 (FIG. 26) of body tissue, withthe flexible wall 606 of the cannula 600 in the retracted conditionillustrated in FIG. 29. This enables the cannula 600 to be insertedthrough a relatively small incision formed in the skin enclosing thecontinuous mass of tissue. Prior to insertion of the cannula 600 intothe continuous mass of tissue, the continuous mass of tissue is free ofany openings. As the cannula 600 is inserted into the continuous mass ofbody tissue with the flexible wall 606 in the retracted condition ofFIG. 29, the relatively smooth outer side surface of the cannula iseffective to press aside the body tissue with a minimum of damage to thetissue.

Once the cannula 600 has been inserted into the continuous mass of bodytissue, fluid under pressure is conducted through the passage 614 (FIG.29) to initiate inflation of the flexible wall 606. As this occurs, theflexible wall 606 begins to move away from the main section 601 of thecannula 600. This results in an outer side surface 640 of the flexiblewall 606 pressing against the body tissue to move the body tissue awayfrom the main section 601 of the cannula 600.

As the inflation of the flexible wall 606 continues, the outer sidesurface 640 of the flexible wall disposed on the conical side wall 624presses the tissue both radially outwardly and axially away from thedistal end of the main section 601 of the cannula 600. As this occurs,force is transmitted through the body tissue itself to pull the bodytissue away from the end wall 626 and the distal or axially outer end ofthe cannula 600 to initiate the formation of an open space immediatelyaxially outwardly of the end wall 626.

As the flexible wall 606 continues to move away from the retractedcondition of FIG. 29 toward the fully extended condition of FIG. 30, thetethers 618 are straightened. When the flexible wall 606 reaches thefully extended condition of FIG. 30, the tethers 618 limit outwardmovement of the junction 628 between the end wall 626 and side wall 624.Thus, force is transmitted through the tethers 618 from the junction 628to the main section 601 of the cannula 600 to limit outward movement ofthe junction 628. The reinforcing fibers 632 (FIGS. 32, 33 and 34),cooperate with the tethers 618 to give the side wall 624 the conicalconfiguration shown in FIG. 30 and the end wall 626 a flat annulardisk-shaped configuration.

FIG. 35 illustrates a cannula 210 which is selectively expandable at oneor more selected longitudinal locations. The cannula 210 includes aseries of expandable wall segments defining a longitudinally extendingcentral working passage 212. The expandable segments illustrated includea segment 214, a segment 216, a segment 218, and a segment 220. As anexample, the segment 218 is expandable, upon the introduction of fluidunder pressure, to an expanded condition as illustrated at 222 in FIG.35. Thus, in accordance with the principles illustrated in FIG. 35, acannula or other inflatable medical device can be expanded forpositioning or sealing at one or more selected longitudinal locations.

FIG. 36 similarly illustrates a cannula 224 having a plurality ofexpandable segments 226 through 234 spaced circumferentially around thedistal end portion 236 of the cannula 224. Each of the segments 226-234is selectively expandable, as illustrated-in FIG. 37 showing the segment234 expanded radially outwardly. Accordingly, it is seen that thepresent invention also contemplates a cannula or bladder, or otherinflatable medical device, having a plurality of circumferentiallydisposed segments expandable radially outwardly upon the selectivecontrol of the user of the device. Such selective expansion is useful inselectively positioning the cannula within the tissue in which it islocated, in avoiding damage to certain tissue such as nerve tissue, orin protecting or moving certain tissue selectively.

FIGS. 38-43 illustrate such longitudinally extending radially expansiblesegments of a cannula or bladder or other inflatable medical device inaccordance with the present invention. Each segment shown is one of aseries of similar segments (not shown) spaced circumferentially aroundor formed as part of the wall of a cannula or other device 250. Theexpansible segment 240 illustrated in FIGS. 38-43 is formed as a bellowsor accordion and is expandable to a larger extent at its distal end 244than at its proximal end 242. If the distal end 244 of the expansiblesegment 240 is located adjacent a distal end of a cannula, the cannulawill thus be expandable directly at its tip. The bellows-likeconstruction of the segment 240 provides significant structural rigidityand can transmit in a controlled manner a significant amount of forcebetween its radially outer surface 246 and its radially inner surface248 adjacent-the wall of the cannula 250. The segment 240 is inflated byintroduction of fluid under pressure in a known manner into theinflation space 252 (FIG. 41).

The expandable segment 254 illustrated in FIGS. 42 and 43 has a smoothouter skin 256 supported by a plurality of expandable bellows-shapedhoops 258 spaced longitudinally along the length of the segment 254. Theskin 256 presents a smooth surface to adjoining tissues upon expansionof the segment 254. The hoops 258 provide structural rigidity to thesegment 254, and control the shape of expansion of the skin 256. Itshould be understood that other configurations of the hoops 258, whichsupport the skin 256 of the segment 254, are contemplated.

FIGS. 44 and 45 illustrate expandable devices having textured surfacesfor grip and location control. The retractor 260 illustrated in FIG. 44includes a stalk portion 262 and a bladder portion 264 attached thereto.The bladder portion 264 has a pebbled surface 266. The retractor 268(FIG. 45) has a stalk portion 270 and a bladder portion 272. The bladder272 has a ribbed surface 274. Other types of texturing or finishing maybe provided for an expandable device in accordance with the presentinvention. Any suitable surface configuration may be used to increasethe grip provided between the outer surface of the expandable device andthe tissue which it contacts. It should be noted that the surfacetexturing may also increase the structural rigidity of the expandeddevice.

FIGS. 46-49 illustrate an expanding device 280 which is preshaped andhas a varying wall thickness in its expanding bladder portion. Theexpanding device 280 includes a support member 282 which may be a solidstalk or a hollow cannula or other member. The support member 282 has awidened proximal portion 286, a narrower diameter central portion 288,and a widened distal portion 290.

Bonded to the support member 282 is an expanding bladder 292. Theexpanding bladder 292 includes a proximal portion 294 bonded to theproximal portion 286 of the support member 282. The expanding bladder292 also includes a distal portion 296 bonded to the distal end portion290 of the support member 282. Extending distally from the portion 294is a first expanding portion 298 having a thinner wall section at itsproximal end′300 and a thicker wall section at its distal end 302.Extending. distally from the expanding portion 298 to the thin wallportion 296 is a second expanding portion 304. The second expandingportion 304 is thicker at its proximal end 366, than at its distal end308, having a tapering cross section between the first expanding portion298 and the distal end portion 296.

When in the unexpanded condition, the first and second expandingportions 298 and 304, respectively, of the expandable bladder 292generally lie flat within the recess formed by the narrow portion 288 ofthe support member 282. Upon the introduction of fluid under pressureinto the interior of the bladder 292 through a port (not shown) in thesupport member 282, the bladder 292 expands from the conditionillustrated in FIG. 46 to the-condition illustrated in FIG. 47. Theexpanding portions 298 and 304 expand radially outwardly as illustrated.Because the material of the bladder 292 is thinner at its axially outerend portions 300 and 308, that material stretches more and so thethicker portions 302 and 306 move radially outwardly the greatestamount. The proximal and distal end portions 294 and 296, respectively,are prestretched, that is, stretched to a diameter greater than theirrelaxed condition, for insertion over the support member 282.

Thus, it is seen that the wall thickness of a bladder can be varied atselected locations to control the rates and distances of expansion ofthe bladder portions. Further, portions of the bladder can beprestretched so that they reach their maximum elongation at an earlieramount of expansion. These factors can be used to control the expandedshape of the bladder.

In addition, there may be provided ribs such as the longitudinallyextending ribs 310 illustrated in FIGS. 48 and 49 which are of anincreased wall thickness to provide structural support and expansioncontrol of the elastomeric material of the bladder. The ribs 310 areillustrative of any region of increased wall thickness used to controlthe shape of expansion. Such regions may run longitudinally asillustrated in the device 280, or may run transversely orcircumferentially or in other directions. Taken in combination, all ofthese factors are usable to control the shape of expansion of aninflatable medical device.

In accordance with a further embodiment of the invention, relativelyrigid members such as plates may be molded into relatively flexiblebladder portions to define edges and surfaces, as illustrated in FIGS.50-52. A medical device 312 (FIG. 50) includes a support member 314 suchas a cannula to which is attached an expanding (elastomeric) bladder316. The attachment between the bladder 316 and the support member 314is not shown in these particular cross-sectional views, but may be; inany manner known or as described herein. The bladder 316 has anelastomeric curved portion 318 and an elastomeric portion 319. A plate320 is molded into the bladder 316 and has an edge 322. A second plate324 molded into the bladder 316 has an edge 326. Upon the introductionof fluid under pressure into the volume between the support member 314and the bladder 316, the bladder expands radially outwardly from thecondition shown in FIG. 50 to the condition shown in FIG. 51. Althoughthe elastomeric portion 318 of the bladder 316 changes dimensions, theplates 320 and 324 do not. Thus, the expanding device 316 includes flatsurfaces and edge surfaces which move radially outwardly and maintaintheir rigid condition upon expansion of the device 312. The plates 320and 324 thus control and partially define the expanded shape of thedevice 312.

Alternatively or additionally, as illustrated in FIG. 52, tetheringcords 328 may be employed between the support member 314 and the plates320 and 324. The tethering cords 328 also serve to control and/or limitexpansion of the device 312. Additionally, it can be seen that thedevice of FIG. 52 includes elastomeric bladder portions 330 extendingdirectly between the plates 320 and 324 and the support member 314.Again, this is an alternative form of the construction. Expandingbladders constructed in accordance with the present invention can useany one or more of these various means of controlling or limiting theexpansion of the inflatable medical device, in order to achieve theoptimum structure for the particular application.

FIGS. 53 and 54 further illustrate the use of rigid plates or membersmolded into elastomeric material of an inflatable medical device. Anexpanding bladder 332 is fixed circumferentially by means not shownaround a cannula 334. The cannula 334 includes a cannula wall 336defining a longitudinally extending central opening 338. The expandingbladder 332 includes an elastomeric material 340 within which are moldeda series of relatively rigid plates 342. Between the expanding bladder332 and the cannula wall 336 is a fluid inflation space 344. Upon theintroduction of fluid under pressure into the inflation volume 344, theexpanding bladder 332 expands radially outwardly from the conditionshown in FIG. 53 to the condition shown in FIG. 54. -The elastomericmaterial 340 stretches and elongates circumferentially. The areas of theelastomeric material 340 which are devoid of plates 342 stretch further,thus allowing the plates 342 to separate. The plates 342, which werepreviously in overlapping position, are separated as illustrated in FIG.54. The plates 342 impart structural rigidity and strength to theelastomeric material 340. The invention is not limited to the particularconfiguration of rigid plates and elastomeric material illustrated, butcontemplates any such configuration of relatively rigid members orportions in a relatively stretchable matrix material.

The expanding device illustrated in FIGS. 55 and 56 includes adoubled-over bladder portion to allow maximum expansion at the distalend portion of the device. The device includes a cannula or stalk orother support member 35O. An expanding bladder 352 is bonded at 354 to aproximal portion 356 of the support member 350, and at 358 to a distalend portion 360 of the support member 350. The material of the expandingbladder 352 is doubled-over at 362 adjacent the distal end portion 360.Upon the introduction of fluid under pressure into the volume defined bythe bladder 352, through a fluid supply port 364, the bladder 352expands from the condition shown in FIG. 55 to the condition shown inFIG. 56. Because of the doubled-over portion 362 of the bladder 352,maximum expansion is gained at the distal end of the device rather thanat the center or the proximal end of the expanding bladder 352. Again,such a device may include bladder portions having varying wallthicknesses as discussed above, tethering cords, etc., all to controlthe expanded shape of the device.

The expanding device illustrated in FIGS. 57 through 62 includes adoubled-over bladder portion to allow maximum expansion at the distalend portion of the device in the manner previously described inconnection with FIGS. 55 and 56. The device includes a cannula having amain section or stalk 850. An expanding bladder or flexible wall 852 isbonded at 854 to a proximal end portion 856 of the support member 850and at 858 to a distal end portion 860 of the main section 850 (FIGS. 57and 58). The material of the expanding bladder 852 is doubled-over at862 adjacent to the distal end portion 860.

Upon introduction of fluid under pressure into the volume-defined by thebladder 852, through a fluid supply port 864 (FIG. 57), the bladder orflexible wall 852 expands from the condition shown in FIG. 57 to thecondition shown in FIG. 58. Because of the doubled-over portion 862 ofthe bladder 852, maximum expansion is gained at the distal end of thedevice rather than at the center or proximal end of the expandingbladder 852. Again, such a device may include bladder portions havingvarying wall thicknesses as discussed above or reinforcing fibers tocontrol the expanded shape of the device.

In the embodiment illustrated in FIGS. 57 and 58, tethering cords 870extend from the main section 850 of the cannula to a junction 872between a side wall 874 and an end wall 876 (FIG. 58) of the flexiblewall or bladder 852. The tethering cords 870 limit the extent of outwardmovement of the junction 872 when the flexible wall or bladder 852 isinflated from the retracted condition of FIG. 57 to the extendedcondition of FIG. 58. The side wall 874 of the inflated flexible wallhas a configuration corresponding to the configuration of a portion of acone. The end wall 876 has a configuration corresponding to theconfiguration of an annular disk. However, it should be understood thatthe end wall 876 slopes radially and axially outwardly from a locationwhere the side wall 876 is connected with the main section 850 of thecannula to the junction 872 between the end wall and the side wall 874.

In accordance with a feature of this embodiment of the invention,tethering cords 870 extend outwardly from the distal. end portion of themain section 850 to the junction 872 between the side wall 874 and endwall 876. The tethering cords 870 limit outward movement of the flexiblewall or bladder 852 to assist in imparting the desired configuration tothe bladder when it is in the expanded condition of FIG. 58. Althoughonly a pair of tethering cords 870 are shown in FIGS. 57 and 58, itshould be understood that there is a circular outer array 880 oftethering cords which extend from the main section 850 of the cannulaoutwardly to the junction 872. Although any desired number of tetheringcords could be used, in the illustrated embodiment of the invention,there are nine tethering cords in the circular array 880 of tetheringcords.

In the embodiment of the invention illustrated in FIGS. 59-62, thecannula, has the same general construction as the cannula of FIGS. 57and 58. However, in the embodiment of the invention illustrated in FIGS.59-62, tethering cords are provided between an inner side surface of theside wall 874 of the bladder or flexible wall and the main section 850of the cannula. Since the embodiment of the invention illustrated inFIGS. 59-62 is generally similar to the embodiment of the inventionillustrated in FIGS. 57 and 58, similar numerals have been utilized todesignate similar components.

In accordance with a feature of the embodiment illustrated in FIGS.59-62, an intermediate array 882 of tethering cords 870 extends betweenthe main section 850 of the cannula and the inner side surface of theflexible wall or bladder 852. In addition, an axially inner array 884 oftethering cords 870 extends between the inner side surface of thebladder or flexible wall and the main section 850 of the cannula.

The three arrays 880, 882, and 884 of tethering cords 870 used torestrain outward-movement of the flexible wall or bladder 852 in theembodiment of the invention illustrated in FIGS. 59-62 are effective tocause the extended flexible wall 852 to form an inflated structurehaving a generally conical configuration.

FIG. 63 illustrates an expanding bladder 370 having adjoining portionswith different material characteristics. The device is shown in end viewas disposed circumferentially around a cannula 372. Alternate portions374 of the device are made of a first material having a first set ofmaterial characteristics, while the interfitted portions 376 are made ofa second material having a second set of material characteristics. Forexample, one material may have a lower modulus of elasticity and theother a higher modulus of elasticity. One may be thicker and the otherthinner. one may be elastomeric and the other not. Other combinationsare possible. The portions may be bonded together with adhesive, may beheat-sealed together, or may be solvent sealed. One portion can be madeof metal. PVC is also a suitable material.

Upon the introduction of fluid under pressure into the expanding device370, the portions 374 and 376 expand or move at different rates or intodifferent shapes. The adjoining of different materials can be used tocontrol the expanded shape of the device 370.

FIG. 64 illustrates an expanding device 380 having an expanding bladder382 made of a plurality of materials laminated together. The expandingportion 382 is mounted on a stalk or cannula 384. The bladder 382includes an outer layer 386 of a first material laminated to an innerlayer 388 of a second material. Again, the layers may have differingmaterial characteristics—perhaps polymers with specific propertiesbonded together. For example, the layer 386 may be of a differentdurometer from the material of the layer 388. One of the layers mayprovide structural support while the other provides fluid sealingcapabilities. One layer may provide puncture resistance while the otherprovides expansion shape control. These are some of the many propertiesavailable with such laminated structures.

It should also be noted that the expandable bladder 382 has an expandeddimension many times greater than its unexpanded dimension asillustrated in dashed lines in FIG. 64. This is illustrative of thelarge degree of expansion which the expandable bladders of the presentinvention are able to generate. For example, expandable bladders inaccordance with the present invention have been built having expansionrates of approximately 700% as compared to the unexpanded diameter.

FIG. 65A illustrates a triangular shaped expanding element 400 fixed toa supporting device indicated at 402. The expanding element 400 hasrelatively thin walled portions 404 and a relatively thick wall portion406. Upon the introduction of fluid under pressure into the volume 408defined by the bladder 400, the relatively thin walled portions 404 arestretched to a greater extent than the relatively thick walled portion406. In the similar expanding segment 410 (FIG. 65B), a fiber 412 isembedded in the elastomeric material of the expanding segment to controland limit its expansion. Again, in the similar expanding segment 414illustrated in FIG. 65C, a fiber mesh 416 is embedded in the elastomericmaterial of the expanding segment to strengthen it and to control itsexpansion.

The expanding segments illustrated in FIGS. 66A, 66B, and 66C aresimilar to FIGS. 65A-65C in structural composition but are trapezoidalshaped rather than triangular shaped. FIG. 66A illustrates an expandingsegment 418 connected with a support member 420. The segment 418includes relatively thin walled portions 422 and a relatively thickwalled portion 424. Upon the introduction of fluid under pressure intothe volume defined by the expanding portion 418, the relatively thinwalled portions 422 stretch to a greater extent than the relativelythick walled portion 424 j whereby the relatively thick walled portion424 moves radially outwardly to a greater extent. The expanding segment426 (FIG. 66B) includes an embedded reinforcing fiber 428 for expansioncontrol purposes. The expanding segment 430 (FIG. 66C) includes anembedded fiber mesh 432 for structural support and expansion controlpurposes. The structural compositions and uses of embedded fibers andfiber meshes illustrated in FIGS. 65 and 66 are merely illustrative ofthe various ways in which fibers embedded in the elastomeric material ofan expanding medical device can be used to control the expansionthereof.

FIGS. 67A-67C illustrate the use of overlapping and/or incompletereinforcing fibers for expansion control. A stretchable elastomericmaterial 434 (FIG. 67A) has a plurality of fibers or other reinforcingelements 436 embedded therein. As the stretchable material 434 iselongated, the elastomeric material in the stretch zones 438 (FIG. 67C)between the fiber portions 436 stretches to a greater extent than thematerial immediately around the fibers 436. Further, the embedded fibersresist transverse expansion of the elastomeric material whileencouraging longitudinal expansion as shown. These drawings are merelyillustrative of the use of the concept of overlapping fibers withstretch zones to control expansion rates of an elastomeric material usedin an expanding medical device such as a cannula or catheter. Thepresent invention contemplates other such arrangements of fibers orreinforcing elements in the elastomeric materials.

For example, FIGS. 68-70 illustrates a bladder retractor 440 fixed to acannula 442. A plurality of circumferentially extending reinforcingfibers 444 are embedded in an elastomeric matrix material 446. Inaddition, a plurality of tethering cords 448 extend radially between thecannula 442 and the elastomeric material 446 to limit the radiallyoutwardly expansion. As can be seen in FIG. 70, the reinforcing fibers444 are not complete but rather are broken fibers extendingcircumferentially within the matrix material 446 to define stretch tonesbetween them. Alternatively, the reinforcing fibers may be complete, asillustrated in FIGS. 71 and 72. In the retractor 450 illustrated inFIGS. 71 and 72, a plurality of complete circumferentially extendingreinforcing fibers 452 are embedded in the matrix material 454. Theretractor 456 illustrated in FIGS. 73 and 74 includes a plurality oflongitudinally extending incomplete reinforcing fibers 458 embedded inthe matrix material 460. The retractor 462 illustrated in FIGS. 75 and76 includes a plurality of longitudinally extending complete reinforcingfibers 464 embedded in an elastomeric matrix material 466. Again, theinvention contemplates other such configurations of reinforcing fibersembedded in matrix materials, and is not limited to those shown.

FIGS. 77-79 illustrate a series of expandable bladders laminatedtogether to define a structural unit 470. A series of upperlongitudinally extendable bladders 472 have their ends fixed between anupper member 474 and a central member 476. A series of lowerlongitudinally extending bladders 478 have their ends fixed between thecentral member 476 and a lower member 480. A covering or retainer 482(FIG. 79) may enclose all of the units. Upon the introduction of fluidunder pressure, the bladders 472 and 478 expand longitudinally from thecondition illustrated in FIG. 77 to the condition illustrated in FIG.78. when the bladders 472 and 478 are fully inflated as illustrated inFIG. 54, they define, together with the members 474, 476 and 480 and theretainer 482, a rigid structural unit. This type of laminated bladderconstruction will find many suitable uses. It should be understood thatother configurations of bladders laminated together are contemplated andare within the scope of the invention.

From the above description of the invention, those skilled in the artwill perceive improvements, changes and modifications in the invention.Such improvements, changes and modifications within the skill of the artare intended to be covered by the appended claims.

I claim:
 1. A method of creating a final cavity in a tissue plane withintissue during the performance of a surgical procedure, the methodcomprising the steps of: a) creating an incision into a tissue layer forwhich no potential space or anatomic space exists; b) positioning adissection propagating device including an elongate means and aninflatable means operatively connected to the elongate means in thetissue; and c) deploying the dissection propagating device by inflatingthe inflatable means such that a final cavity is formed within thetissue by force applied against adjacent layers of tissue.
 2. The methodof claim 1 wherein the dissection propagating device is positioned usingblunt or sharp dissection of the tissue.
 3. The method of claim 2wherein blunt dissection is accomplished by insertion of the dissectionpropagating device in a position that precisely defines the intendedplane of dissection.
 4. The method of claim 1 wherein the dissectionpropagating device expands along the axis of insertion.
 5. The method ofclaim 1 wherein the dissection propagating device expands perpendicularto the axis of insertion.
 6. The method of claim 1 wherein thedissection propagating device expands in a plurality of directions fromthe axis of insertion.
 7. The method of claim 1 wherein the dissectionpropagating device further comprises; a balloon.
 8. The method of claim7 wherein the dissection propagating device is positioned in the tissuein a deflated condition.
 9. The method of claim 7 wherein a final cavityof a predefined size and shape is created when the balloon is inflated.10. The method of claim 9 wherein the final cavity of a predefined sizeand shape is created by the inflation of a balloon having a variablewall compliance matched to the size and shape of expansion desired. 11.The method of claim 9 wherein the variable compliance is produced byvarying the wall thickness of the balloon.
 12. The method of claim 7wherein unrolling the balloon generates force for dissecting the tissueto form the final cavity.
 13. The method of claim 7 wherein unfoldingthe balloon generates force for dissecting the tissue to form the finalcavity.
 14. The method of claim 7 wherein expanding the balloon producesconcentric or eccentric force.
 15. The method of claim 7 wherein theballoon is inflated with fluid.
 16. The method of claim 7 wherein theballoon is inflated with gas.